Tce. Van Weering et al., Recent sediments, sediment accumulation and carbon burial at Goban Spur, NW European Continental Margin (47-50 degrees N), PROG OCEAN, 42(1-4), 1998, pp. 5-35
To quantify recent sediment accumulation, carbon fluxes and cycling, three
N.W. European Continental Margin transects on Goban Spur and Meriadzek Terr
ace were extensively studied by repeated box- and multicore sampling of bot
tom sediments. The recent sediment distribution and characteristics appear
directly related to the near-bed hydrodynamic regime on the margin, which a
t the upper slope break on the Goban Spur results in along-slope and period
ic off-slope directed transport of particles, possibly by entrainment of pa
rticles in a detached bottom or intermediate nepheloid layer. From the shel
f to the abyssal plain the surface sediments on the Goban Spur change from
terrigenous sandy shelf sediments into clayey silts. Pb-210 activity decrea
ses exponentially down core, reaching a stable background value at 10 cm (s
hallower stations) to 5 cm (deeper stations) sediment depth. Pb-210 profile
s of repeatedly sampled stations indicate negligible annual variability of
mixing and flux. The Pb-210, flux to the sediment shows a decreasing trend
with increasing water depth. Below about 2000 m the average Pb-210(xs) flux
is about 0.3 dpm cm(-2) y(-1), a third of the fluxes measured on the shelf
and upper slope stations. Sediment mixing rates (D-b) correlate with macro
- and meiofaunal density changes and are within the normal oceanic ranges.
Lower mixing rates on the lower slope likely reflect lower organic carbon f
luxes there. Mass accumulation rates on Meriadzek Terrace are at maximum 80
g m(-2) y(-1), almost twice as high as at Goban Spur stations of comparabl
e depth. A minimum accumulation rate of 16.6 g m(-2) y(-1) is found at the
Goban Spur upper slope break. Organic carbon burial rates are low compared
to other margins and range from a lowest value of 0.05 g m(-2) y(-1) at the
upper slope break to 0.11 g m(-2) y(-1) downslope. A maximum organic carbo
n burial rate of 0.41 g m(-2) y(-1) is found on Meriadzek Terrace. Carbonat
e burial rates increase along the northern transect from the shelf (13 g m(
-2) y(-1)) via a low (9.3 g m(-2) y(-1)) on the upper slope break to the de
ep sea (30.7 g m(-2) y(-1)). Carbonate burial is highest on Meriadzek Terra
ce (44.5 g m(-2) y(-1)). The N.W. European Margin at Goban Spur and Meriadz
ek Terrace cannot be considered a major carbon depocenter. (C) 1998 Elsevie
r Science Ltd. All rights reserved.